VENUS. 407 



sub-biangulated (the upper angle is the more distinct, and 

 generally is the more projecting), the posterior edge being- 

 more or less perpendicular ; the hinder dorsal edge, Avhich in 

 the young is straightish, becomes convex, or even arcuated, 

 in the adult, but never slopes to any considerable extent, and 

 not unfrequently declines in but a very trifling degree. The 

 umbones lean remarkably forward, but are not by any 

 means prominent ; the beaks are acute and distinct. The 

 ligament, which is sunken and moderately large, occupies 

 about one-half the length of the not very profound dorsal 

 excavation or lozenge, whose shelving and subequal sides 

 are either colourless, or only irregularly painted. The 

 lunula is rather short, and often rufous. The interior is of 

 an uniform whitish hue ; the muscular scars are large, and 

 the pallial sinus rather small and abbreviately linguiform ; 

 the basal margin, which is very broad, is strongly but 

 finely and very closely crenated. Besides the three very 

 divergent teeth (of which the central, by far the largest, is 

 subbifid in the left valve), there is a minute anterior den- 

 ticle at the lower part of the hinge margin in the left valve, 

 and a corresponding indistinct socket in the right one. 



Fine examples occasionally attain to the length of two 

 inches ; their breadth is somewhat less. The animal is 

 thick and white ; but the details of its structure have yet 

 to be observed. 



This is one of our least common Veneres, and is rarely 

 obtained in any abundance. It is occasionally taken in 

 Northumberland and Durham (Alder) ; at Scarborough 

 (Bean) ; West Bay of Portland in fifteen fathoms (M'A. 

 and E. F.); South Devon (Mont.); Guernsey (S. H.) ; 

 Milford Haven (M* Andrew and E. F.), and elsewhere on 

 the Welsh coast. In from twelve to twenty-five fathoms 

 on the Manx Coast (E. F.). Both sides of Ireland (Thomp- 



